To provide an internal combustion engine for reducing the mounting number of sensors for detecting vibration generated from respective solenoid driving valve and sufficiently securing reliability on the detection in a multicylinder internal combustion engine having the solenoid driving valves.

Intake side solenoid driving mechanisms A30, B30 arranged over adjacent cylinders #1, #2 and similarly a single intake side G sensor 30a in the vicinity of an intermediate position between intake side solenoid driving mechanisms C30, D30 are installed on the intake side of the axis P on a cylinder head 1a of a series four-cylinder internal combustion engine. This single intake side G sensor 30a is used in common for detecting the vibration on the respective four intake side solenoid driving mechanisms 30.